TNS or TNCS supply?

[swifters]

Hi all, please see attached? TNS or TNCS supply? Looks like it could be a TNCS but no notice to say that it is?

 

[trev]

If someone is stupid enough to take the cover off the service head then they deserve all they get I'd say mate.

 

[pete555]

If someone is stupid enough to take the cover off the service head then they deserve all they get I'd say mate.

may be so but us old experienced sparks have a duty to try and save the youth from themselves May be not but it sounds as though we care but I agree with you what possess them to do such stupid things and then ask for help

 

[trev]

I do try to pass my skills on as much as I can and enjoy doing it but sometimes what someone needs is a bloody good rollocking. I got enough of them when serving my time to know whether something I'm thinking about doing is dangerous or not.

 

[derek preece]

As with a fair bit of bs7671, it seems open to interpretation. Granted, NICEIC isn't Gospel but having seen many a burn mark in electrical installations, I would think it best practice to avoid and ideally replace any wooden fusebox's and sockets mounted in skirting. Fire requires a heat source, fuel and oxygen. If you can remove the fuel, the fire wont start!

Surely if you remove the heat source by ensuring the circuit is designed, installed, maintained and used correctly then fire shouldn't arise. Most burn marks I've ever seen have been caused by a poor standard of workmanship by the installer or incorrect design or use. Plastic burns as well doesn't it (although I'm not sure what temperature would be required)?

 

[richy3333]

Many thanks to all the helpful people out there. No where in the manual does it say to join the N and E leads together but I have and these are the results I eventually got for my house which I know is TNCS. PSC between line and earth 0.28 ohms and 0.891ka. PSC between line and neutral 0.29 ohms and 0.861ka. So, many thanks. That seems to all make sense.

However, the di-log leads are not at all easy to connect together! First result came up on screen FUSE and secondly the results did fluctuate. It was only on the third test that I got these results. Got reading's fluctuating between 0.32 ohms and 0.17 ohms so not necessarily all that easy to interpret results....

A bit surprised your asking this type of question mate when your website says:

Electrical inspection and testing is where you can sort the men from the boys as to perform a electrical installation condition report you need to have a firm grasp of Zs,Ze,R1,R2,r1,r2, values along with knowing the in’s and out’s of continuity testing, insulation resistance testing and RCD testing, to name but a few

 

[pete555]

I do try to pass my skills on as much as I can and enjoy doing it but sometimes what someone needs is a bloody good rollocking. I got enough of them when serving my time to know whether something I'm thinking about doing is dangerous or not.

me too and we learnt not to be stupid mate

 

[Silly Sausage]

My early thoughts on this thread a few hours ago were...
If you're out in the field testing, you should know what your test gear is capable of, and, you should know how to use it!
It'll save you a ton of grief, learn how to use it!.

 

[KAS1]

I'd just checked out the website as well, it's a wonderful thing "The Web" people can describe themselves very well on the internet or get someone to do it for them lol

 

[GLENNSPARK]

Blimey, why is everyone on their high horse today! My dilog 9083p takes the pscc and pefc at the same time and only when it detects line, neutral and earth. I then press the function key to find the highest kA and ze values between the two. If there's an alternative way of finding the kA value I would like to know it but don't try and belittle me! I'm sure I'm as every bit as competent as yourself if not more so!

Regards the socket outlets in skirting’s, I have never come across sockets in skirting’s that have put under undue pressure on the supply or load cables. I have however, seen them with wooden back boxes. Surely if the cables arched/overloaded then there is a fire risk with them being mounted in the flammable wooden skirting’s? Granted most are in metallic back boxes but not all.

take a Zpn... then a Zpe....if TN-C-S the KA should be substantially the same for both tests....

 

[swifters]

I'm sorry but some of the criticsm is a little unjust. Yes, the di log is a very easy to use multi function tester but no where in the manual does it say to join the neutral and earth leads together to perform a seperate pfc to distinguish between tns and tncs. Additonally, the way the readings naturally fluctuate I would say it is not always easy to interpret these results.

I can distinctly remember having a high ze value of 0.9 ohms on one job. Uk power networks came out and there was some ambiguity as to whether it was tns or tncs. He removed the service head cover and showed me it was tns. He didn't isolate the supply before removing this cover. He then took his own ze readings and they were just under 0.8 ohms. When I said I was getting readings of 0.9 ohms earlier he just shruged his shoulders.

 

[swifters]

Surely if you remove the heat source by ensuring the circuit is designed, installed, maintained and used correctly then fire shouldn't arise. Most burn marks I've ever seen have been caused by a poor standard of workmanship by the installer or incorrect design or use. Plastic burns as well doesn't it (although I'm not sure what temperature would be required)?

Totally agree but even then electrical faults can still occur.

 

[GLENNSPARK]

I'm sorry but some of the criticsm is a little unjust. Yes, the di log is a very easy to use multi function tester but no where in the manual does it say to join the neutral and earth leads together to perform a seperate pfc to distinguish between tns and tncs. Additonally, the way the readings naturally fluctuate I would say it is not always easy to interpret these results.

I can distinctly remember having a high ze value of 0.9 ohms on one job. Uk power networks came out and there was some ambiguity as to whether it was tns or tncs. He removed the service head cover and showed me it was tns. He didn't isolate the supply before removing this cover. He then took his own ze readings and they were just under 0.8 ohms. When I said I was getting readings of 0.9 ohms earlier he just shruged his shoulders.

so you thought you`d follow suit did you?...
hmm.
not only do you put yourself (and possibly others) at risk....but it is an offence to interfere with DNO equipment...
I and others have explained to you (i thought quite clearly) as to how to test to verify beyond any reasonable doubt as to the earthing arrangements that cannot be verified by visual alone.
The person who came out and `removed the cover`.....just for your benefit? was a DNO operative.....
can you see the difference?

 

[telectrix]

so you thought you`d follow suit did you?...
hmm.
not only do you put yourself (and possibly others) at risk....but it is an offence to interfere with DNO equipment...
I and others have explained to you (i thought quite clearly) as to how to test to verify beyond any reasonable doubt as to the earthing arrangements that cannot be verified by visual alone.

and , of course, you've never pulled the bullit to determine it's type and rating, have you? :lipsrsealed2:

 

[Sharpend]

Maybe but as long as you're not expecting the next step to dig up the incoming cable just to be sure!

This thread is a clear example of how not to be an electrician. I'd suggest become an apprentice or train as a DNO operative but don't just assume both!

 

[swifters]

I really don't mean to rile anyone on here as most people have been really helpful. There was no security cord around the main fuse and I put everything back as was. Infact there was a cut out blank that was sitting slightly incorrectly and I made sure this sat correctly between the grooves.

Lastly, I've just performed a PSC on my own house and got the following readings 0.17 ohms and 1.45 ka. Then 0.23 ohms and 1.04 ka.... In the time its taken me to switch my probes around on the neutral and the earth the results have changed... I know I'm on a TNCS but how do you know for sure when on site? It's quite an important thing to get right surely...